Quantitative and structural determination of pseudoephedrine sulfate and its related compounds in pharmaceutical preparations using high-performance liquid chromatography

A Chemometric Strategy in the Development of a RP-UPLC Method for the Quantitative Resolution of a Two-Component Syrup Formulation

A novel chemometric strategy was implemented in the development of a new ultraperformance liquid chromatography method for the quantitative estimation of guaifenesin and pseudoephedrine hydrochloride in a two-component syrup formulation with minimal experimental effort, time and reagent. A full factorial design with three factors was investigated to find optimal working conditions of chromatographic factors (column temperature, flow rate, and 0.1 M H3PO4% in mobile phase) that affect the chromatographic separation. Then, optimum experimental conditions providing adequate separation of the analyzed drug substances within the short runtime were determined. Under optimal experimental conditions, the retention times for guaifenesin and pseudoephedrine hydrochloride were obtained as 0.817 and 1.430 min, respectively. In the optimized RP-UPLC method, chromatographic response was reported as a linear function of concentration between 5.0 and 80.0 μg/mL for guaifenesin and 10.0-90.0 μg/mL for pseudoephedrine hydrochloride. The proposed method was carefully validated and successfully applied to quality control and analysis of a cough syrup preparation containing guaifenesin and pseudoephedrine hydrochloride. Consequently, the proposed reversed-phase ultraperformance liquid chromatography method provided an opportunity to quantify relevant drugs with small amount of reagents and short runtime.

Esterification of pseudoephedrine hydrochloride by citric acid in a solid dose pharmaceutical preparation

Esterification of pseudoephedrine hydrochloride (PSE) by citric acid was observed in a solid dose pharmaceutical preparation at room temperature and accelerated stability condition (40°C/75% relative humidity). The esterification of PSE with citric acid was confirmed by a solid-state binary reaction in the presence of minor level of water at elevated temperature to generate three isomeric esters. The structures of the pseudoephedrine citric acid esters were elucidated using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy (NMR). Occurrence of esterification in solid state, instead of amidation which is generally more favorable than esterification, is likely due to remaining HCl salt form of solid pseudoephedrine hydrochloride to protect its amino group from amidation with citric acid. In contrast, the esterification was not observed from solution reaction between PSE and citric acid.

Monitoring phospholipids for assessment of matrix effects in a liquid chromatography-tandem mass spectrometry method for hydrocodone and pseudoephedrine in human plasma

Matrix effects resulting in ion suppression or enhancement have been shown to be a source of variability and inaccuracy in bioanalytical mass spectrometry. Glycerophosphocholines may cause significant matrix ionization effects during quantitative LC/MS/MS analysis and are known to fragment to form characteristic ions (m/z 184) in electrospray mass spectrometry. This ion was used to monitor ion suppression effects in the determination of hydrocodone and pseudoephedrine in human plasma as a means to track and avoid these effects. The m/z 184 ion fragment was detected in both plasma extracts and solutions of phosphatidylcholine. Post-column infusion studies showed that the ion suppression for both drugs and internal standards correlated with the elution of phospholipids. HPLC conditions were adjusted to chromatographically resolve the peaks of interest from the phospholipids. Upon repeated injection, the elution time of the phospholipids decreased while elution of the analyte peaks remained unchanged. This resulted in co-elution and significantly affected peak shape and internal standard response for the analytes. It was decided to use the phospholipid fragment to monitor this matrix effect in validation samples. The resulting method demonstrated intra-day and inter-day precision within 4.5 and 5.6% for hydrocodone and pseudoephedrine, respectively, and accuracy within 8.9 and 8.7% for hydrocodone, and pseudoephedrine, respectively. There was no statistically significant difference in the internal standard response for the determination with and without monitoring the phospholipid fragment ion. We found that monitoring the phospholipid fragment was useful in method development to avoid the matrix effects, and in routine analysis to provide a practical way to ensure the avoidance of matrix effects in each individual sample.

Sensitive bioassay for the simultaneous determination of pseudoephedrine and cetirizine in human plasma by liquid-chromatography–ion trap spectrometry

A liquid chromatography-ion trap mass spectrometry coupled with electrospray ionization (HPLC-ESI-ion trap mass spectrometry) method for simultaneous determination of cetirizine and pseudoephedrine in human plasma is presented. Chromatographic separation was performed on a Hypurity C18 column (Thermo Hypersil-Keystone 2.1 mm x 150 mm, 5 microm, USA), The mobile phase was composed of 65% methanol and 35% water (contained 0.1% formic acid, 10 mM ammonium formate), which was run with a flow-rate of 0.2 ml/min at 40 degrees C. Quantitation was achieved by monitoring the product ions at m/z 166-->m/z 148 (pseudoephedrine), m/z 389.9-->m/z 201.1 (cetirizine), m/z 264-->m/z 246 (tramadol, IS). The calibration curve of pseudoephedrine and cetirizine was established with standard solutions. The limit of detection for pseudoephedrine and cetirizine each was 5 ng/ml. This simplified analytical method is sensitive, specific and accurate enough for simultaneous determination of pseudoephedrine and cetirizine in human plasma and is successfully applied to the pharmacokinetic study of pseudoephedrine and cetirizine.

Construction and Performance Characterization of Ionselective Electrodes for Potentiometric Determination of Pseudoephedrine Hydrochloride Applying Batch and Flow Injection Analysis Techniques

New pseudoephedrine selective electrodes have been constructed of the conventional polymer membrane type by incorporation of pseudoephedrine-phosphotungstate (PE-PT) or pseudoephedrine-silicotungstate (PE-SiT) ion-associates in a poly vinyl chloride (PVC) membrane plasticized with dibutyl phthalate (DBP). The electrodes were fully characterized in terms of the membrane composition, temperature, and pH. The electrodes exhibited mean slopes of calibration graphs of 57.09 and 56.10 mV concentration decade(-1) of PECl at 25 degrees C for (PE-PT) and (PE-SiT) electrodes, respectively. The electrodes showed fast, stable, and near-Nernstian response over the concentration ranges 6.31 x 10(-6)-1.00 x 10(-2) and 5.00 x 10(-5)-1.00x10(-2) M in the case of PE-PT applying batch and flow injection (FI) analysis, respectively, and 1.00 x 10(-5)-1.00 x 10(-2) and 5.00 x 10(-5)-1.00x10(-2) M in the case of PE-SiT for batch and FI analysis system, respectively. Detection limit was 5.01x 10(-6) M for PE-PT electrode and 6.31x10(-6) M for PE-SiT electrode. The electrodes were successfully applied for the potentiometric determination of pseudoephedrine hydrochloride (PECl) in pharmaceutical preparations with mean recovery 101.13 +/- 0.85% and 100.77+0.79% in case of PE-PT applying batch and flow injection systems, respectively, and 100.75+0.85% and 100.79 +/- 0.77% in case of PE-SiT for batch and flow injection systems, respectively. The electrodes exhibited good selectivity for PECl with respect to a large number of inorganic cations, sugars and amino acids.